The present invention relates to the fortification of food and more particularly to the fortification of food with calcium.
Calcium is an important element in human diets for adequate bone formation and maintenance as well as other metabolic functions, e.g., nerve transmission, blood clotting, proper cell function and muscle contraction. It is common practice to fortify food products with calcium sources which are either insoluble or soluble at around neutral pH. Many of the calcium sources currently used for fortification are insoluble or substantially insoluble at around neutral pH, e.g., calcium carbonate, calcium phosphates, calcium citrate and other salts of calcium. These materials result in precipitation and a chalky mouth feel. Other calcium sources are soluble or substantially soluble at around neutral pH such as calcium chloride, calcium lactate and a few organic acid salts of calcium, but these react with milk proteins resulting in undesirable coagulation and sedimentation.
It is also common practice to stabilize or reduce the sedimentation of the calcium and milk proteins in the milk beverages fortified with calcium sources by adding carrageenans, pectins and/or other gums, but such materials impart an undesirably high viscosity to milk. Protein destabilization, e.g., precipitation and coagulation, is mainly attributed to free calcium ions in the system.
It would be highly desirable to have a calcium source to fortify milk beverages and other dairy based products without coagulation and sedimentation, with improved palatability.
The invention relates, in a first embodiment, to a fortified foodstuff comprising a fortifying amount of a complex of calcium and a hydrolyzed polysaccharide having a degree of polymerization sufficient to form a complex with calcium while substantially preventing sedimentation upon storage of the foodstuff for at least about three weeks. The hydrolyzed polysaccharide may be, for example, a hydrolyzed carboxymethylcellulose, a hydrolyzed hemicellulose, a hydrolyzed alginate or a hydrolyzed gum, such as carrageenan, guar gum, xanthan gum, gellan gum or gum arabic. These complexes may be prepared by forming a polysaccharide and thereafter hydrolyzing the same to the desired size, or alternately with the use of oligosaccharides prepared from monosaccharide monomers using various means such as microbial, enzymatic or chemical reactions in a manner well known in the art. In a preferred embodiment the hydrolyzed polysaccharide has a degree of polymerization of less than 50, preferably from about 1 to 25.
In an alternate embodiment of the invention the foodstuff comprises a fortifying amount of a complex of calcium and a hydrolyzed polysaccharide together with an acid, preferably an organic acid selected from the group consisting of citric, fumaric and tartaric acid.
The foodstuff used in forming the fortified foodstuff of the invention may be, for example, a dairy based product such as a milk product, a confectionery product, ice cream or a beverage such as a juice and may be frozen, refrigerated or shelf-stable.
In a further embodiment of the invention, the hydrolyzed polysaccharide has a degree of polymerization of 1 to 800. Preferably, the hydrolyzed polysaccharide is a hydrolyzed pectin. The hydrolyzed pectic is preferably demethoxylated to more than 50%.
In a preferred embodiment, the amount of the complex present in the fortified foodstuff is from about 0.05 to 5% by weight based upon the weight of the foodstuff.
In still another embodiment, the invention is directed to a process for preparing a calcium fortified foodstuff. The process comprises adding to the foodstuff a fortifying amount of a complex of calcium and a hydrolyzed polysaccharide, such as those described above, wherein the hydrolyzed polysaccharide has a degree of polymerization sufficient to allow calcium binding without subsequent gelation and thus sedimentation of the hydrolyzed polysaccharide. The foodstuffs thus prepared are stable, i.e., without coagulation and/or sedimentation, and benefit from improved palatability compared to foodstuffs without the complex of the invention. Preferably the degree of polymerization of the complex ranges from about 1 to 25.
In a preferred embodiment of the method, hydrolyzed pectin is selected as the hydrolyzed polysaccharide.
In an alternate embodiment, the method comprises forming a complex by combining calcium and a hydrolyzed polysaccharide together with an acid. The acid may be an organic acid. The complex may be formed as a solution, a suspension or, if desired, in a dry form. The complex may be prepared, for example, by mixing a solution or suspension of a calcium salt with a solution or suspension of a hydrolyzed polysaccharide wherein from about 0.05 to 5% by weight of the complex is added to the foodstuff. Additionally, the complex may, if desired, be dried prior to adding it to the foodstuff. In an alternate embodiment the fortified foodstuff can be made with a stabilizing effective amount of a gum or an emulsifier.
The hydrolyzed polysaccharides may be derived from any negatively charged polysaccharide, e.g., a hydrolyzed carboxymethylcellulose, hemicellulose, alginate or gum such as a carrageenan, guar gum, xanthan gum, gellan gum or gum arabic, or mixtures thereof. Advantageously and preferably, a hydrolyzed pectin is used. Pectins typically have a molecular weight of about 10,000 to about 150,000 and are methoxylated from about 20% to about 80%. Preferably, pectins have a molecular weight of about 10,000 to about 50,000 and more preferably a molecular weight of about 10,000 to about 30,000. Pectins are methoxylated from about 20% to 80%, preferably from about 50% to about 75% and more preferably from about 60% to about 70%.
An important feature of the hydrolyzed polysaccharides of the invention in general, and hydrolyzed pectin in particular, is the Degree of Polymerization (DP) of these compounds. Pectins, for example, typically have a DP of from about 50-800. The degree of polymerization is related to the quality of the fortified foodstuff produced in accordance with the invention in that, as the DP is reduced, there is a corresponding improvement, i.e., reduction, in the amount of sedimentation encountered. Lowering the DP of the hydrolyzed polysaccharide additionally results in longer-lasting suspensions, i.e., in contrast to products formed with polysaccharides having higher DP""s, and also permits the addition of greater amounts of calcium into the specification with little or no sedimentation in the final product. For example, a product comprising a hydrolyzed polysaccharide with a DP of about 50 to about 80 is typically stable without sedimentation for up to about three weeks under refrigerated conditions, typically about 40xc2x0 F., while reducing the DP of the polysaccharide to a value of about 1-25 results in a fortified foodstuff which may be stable for up to about two months under refrigerated and room temperature conditions, particularly when such product is subject to an ultra-high temperature pasteurization treatment in a manner well-known to those of ordinary skill in the art. Typically, the amount of hydrolyzed polysaccharide present in the complex is in a calcium to hydrolyzed polysaccharide ratio of about 1:1.5-22.5, preferably in a ratio of about 1:2-13, more preferably in a ratio of about 1:3-7.
Although pectins may theoretically be hydrolyzed to a DP of 1 and completely demethoxylated, these levels are difficult to achieve. Preferably when used in the invention the hydrolyzed polysaccharides in general, and pectin in particular, have an average DP of from about 1 to 25 and more preferably from about 1 to 10. The hydrolyzed pectin is conveniently demethoxylated such that less than 50% and preferably less than 75% of the pectin""s galacturonic acid monomers contain methyl esters.
The hydrolysis (and the demethoxylation when the polysaccharide is pectin) may be carried out by chemical, physical or enzymatic means or any combination thereof. The enzymatic hydrolysis may be carried out, for instance, by a process as described in U.S. Pat. No. 5,958,474 issued Sep. 28, 1999. The chemical hydrolysis may be carried out by treatment with an acid but is preferably carried out by treatment with an alkali. The physical hydrolysis may be carried out by shear. As these treatments are already generally known or disclosed in the art, there is no need to further describe them herein.
The complex of calcium and the hydrolyzed polysaccharide may be prepared by mixing an aqueous solution or suspension of a calcium compound with an aqueous solution or suspension of a hydrolyzed polysaccharide. The calcium compound may be calcium hydroxide or calcium oxide or it may be derived from one or more of several salts, e.g., the chloride, carbonate, phosphate, sulfate, citrate, nitrate, or acetate. When the complex includes calcium and a hydrolyzed polysaccharide together with an acid, the acid is preferably an organic acid. The acid may be selected from citric, fumaric, tartaric, malic, lactic, succinic, acetic, oxalic and ascorbic acids. More than one acid may be used if desired. Typically the acid is present in a calcium to acid ratio of about 1:1-5.5, preferably in a ratio of about 1:1.5-5, and more preferably in a ratio of about 1:2-4.
The complex is formed as an aqueous solution or suspension and, if desired, may be dried, for instance to a powder, by various methods commonly known to those skilled in the art.
The fortified foodstuff comprising a fortifying amount of a complex of calcium and a hydrolyzed polysaccharide (and optionally including an acid) may be prepared by mixing the foodstuff with the complex. The complex may be in the form of a solution or suspension or it may be in a dry form such as a powder.
The amount of complex present in the fortified foodstuff may be from about 0.05% to about 5%, preferably from about 0.1% to about 2.5%, and more preferably from about 0.2% to about 1% by weight based on the weight of the foodstuff.
The foodstuff may subsequently be further stabilized by adding gums, e.g., carrageenans, gum arabic, guar gum, gellan gum, xanthan gum etc., or by adding emulsifiers, e.g., mono- or di-glycerides, lecithin or sodium stearyl lactate.
Due to the stability of the complex, the fortified foodstuff may be frozen, refrigerated or shelf-stable.